The image you link is just the green background. The pdf has more than just a green basketweave pattern. It has graphics (lines) and text.
Take for example box 6c on the birth certificate. It says “6c Name of Hospital or Institution (if not in hospital or institution, give address)” but when you turnoff the text layer, the green background says “6c N f H al I (if h tal add “. Why would a forger put some of the letters on the background and some on the text layer?
An image like that can be starting point for an electronic assemblage.
Actual security paper would have “VOID” all over it when scanned or copied. THIS DOESN’T.
Additionally, this is yet another version purported to be a “scan of the original” This original has magic powers, the background keeps changing!